Using the “SendMessage” service on my MailThing will work, but if I set up a Notification to trigger from an event, no email is sent

I’ve had this same issue with the “Notifications” entities as well. As stated in this topic (https://community.ptc.com/thingworx-developers-185/email-notification-doesn-t-work-90553). Using the “SendMessage” service on my MailThing will work, but if I set up a Notification to trigger from an event, no email is sent.  I set up a subscription to log a message on the same event and it DOES log the message.  Our ThingWorx platform is configured as a HA cluster, currently running version 10.1.1, but this issue has been across multiple versions.

Performing a rolling restart of my individual server nodes seems to resolve the problem and the Notifications ARE triggered for a while, but eventually they stop working again.  I’m curious to know if more people have experienced this issue.

UPDATE: Performing the rolling restart (cycling nodes while platform remains up) is NOT working in today’s instance of this problem.  I believe it worked in the past but seemingly not today.  Maybe the problem has something to do with the cache/Ignite instances?